Lithium-Ion (“Li-Ion”) 18650 cells (and other batteries) have a slight chance of spontaneously shorting, which heats the interior gradually until a separator film within the cell melts, resulting in an internal short. Consequently, an explosive release of thermal energy can be triggered. The explosion can cause an end cap of the shorted cell to rupture. A flare briefly emerges (e.g., of around 1 second) from that ruptured end cap. For a minute or so, the cell's materials combust, releasing heat and driving the shorted cell to about 500 degrees Celsius (“C”) or greater.
If there are any neighboring cells that are consequently heated near or above a critical temperature (e.g., around 130° C.), the neighboring cells can also short with the same consequences causing additional explosions and ruptures; hence giving the well-known problem of thermal runaway propagation. The well-known Boeing battery problem is also of this nature. In Tesla's electric automobiles, the battery cells have an active cooling system to prevent such thermal runaway propagation.
However, there is a desire to seek a passive solution suitable for battery modules of arbitrary cell sizes and shapes. Therefore, there exists a need for a new system, method, and apparatus for preventing thermal runaway propagation for cells in an energy storage device.